1. Field of the Invention
The present invention relates to a method and apparatus for relieving motion sickness. More particularly, the present invention is related to providing individual sensory signals that correspond to the motion of a craft, or in another aspect, proximity of potential obstacles, so that the individual may use these signals to improve a sense of equilibrium or to avoid collision with the obstacles.
2. Discussion of the Background
Essentially, motion sickness occurs as a result of an unusual motion experience. When a person is unable to predict or anticipate this unusual motion, the person's equilibrium may be effected. The phenomenon of motion sickness may be derived from a principle researched by Dr. David Winters, a retired University of Waterloo professor, and which is referred to as "The Principle of Indeterminacy."
The principle of indeterminacy describes a human's natural ability to identify changes in the neuromuscular skeletal system and to adapt to a new optimum motion. For example, if a prosthetic leg does not offer comparable function, an amputee will favor the remaining leg. Thus, the residual limb becomes weaker and the remaining leg becomes stronger. The option to utilize the prosthesis or the natural leg represents a conflict, i.e., between walking in a conventional symmetrical manner or favoring the natural leg. The person, without conscious volition, chooses favoring the natural side when the choice is perceived by the human's body as optimal. Currently, it is not known for certain which senses are most influential in making this choice. However, it is likely that pain and comfort, proprioceptive, vestibular, and ocular inputs affect this choice.
Similarly, motion sickness results from a conflict between these vestibular, ocular and proprioceptive inputs. For example, conventional wisdom among charter boat operators is that charter boat captains do not get seasick, unless they spend a significant amount of time below deck, whereas captains of cruise ships are known to be somewhat more susceptible to motion sickness. This is because a charter boat captain usually sits high in the cabin, a position from where he can observe quite clearly what the relatively small charter boat is about to experience. Thus, he has accurate visual data which reconciles a conflict between the vestibular, ocular, and proprioceptive inputs. On the contrary, the captain of a large cruise ship cannot see what is taking place immediately in front of the ship's bow. Thus, a conflict between the vestibular, ocular, and proprioceptive data is not resolved.
Motion sickness is very costly for many industries. For example, the airline industry loses millions of dollars per year from passengers who are unwilling to travel because they experience motion sickness. The same can be said for cruise ships. In addition, if a person experiences motion sickness while operating a dangerous vehicle, injury or even a loss of life may occur.
Thus, a need for a device which relieves or prevents motion sickness will have a significant impact on society. One proposed motion sickness device is that described in Ferguson (U.S. Pat. No. 5,161,196). Ferguson discloses positioning an array of sound emitters at the sides of an enclosure and varying the sound levels from selected emitters in response to changes in the enclosure's movement. To an individual, the sound source is not perceived as rolling with the vehicle but rather is inertially stable while the vehicle rolls relative to the sound source. That is, Ferguson is directed to creating an artificial sound horizon which is acoustically perceivable to the individual and continuously maintaining the sound horizon substantially positionally stationary with reference to a fixed horizon of the enclosure.
However, one problem with Ferguson is that an artificial sound horizon is created. This artificial sound horizon (i.e., between sound emitters at opposite sides of the enclosure) may cause an individual to experience further motion sickness because a conflict is created between the vestibular, ocular, and proprioceptive inputs and the artificial sound horizon. Further, another problem with Ferguson is that an array of sound emitters (e.g., speakers) placed at specific locations chosen in accordance with a predicted motion of the enclosure are required. That is, the speakers are required to be located in opposite sides of the enclosure.